Hydraulic lifting jack



April 11, 1950 F. CURTIS 2,503,659

HYDRAULIC LIFTING JACK Filed April 29, 1946 2 Sheets-Sheet l m g 3 47 4f 454 '55; l 1-: ii 60 Q 45 INVENTOR. REF/MK CURTIS H'TTOENEY April 11, 1950 Filed April 29, 1946 HYDRAULIC LIFTING JACK F. CURTIS 2 Sheets-Sheet 2 INVENTOR. F/WK Cue T16 Patented Apr. 11, 1950 UNITED STATES PATENT OFFICE,

HYDRAULIC LIF TIN G JACK" Frank Curtis, Seattl e,,Wash,

Application April 29,1946, Serial No. 665 778 S t Claims. (Cl. 251 -93);

This invention relates to lifting: jacks and: 1t H has reference more particularly to hydraulic;

jacks of atype'especially adapted for-house lifting operations and for various analogous uses;

It is the 1 principal "object of this invention to provide a jack having a substantial lifting range; which is extremely powerfuland is so designedas to insure maximum stability when used with:supe

porting cribbing. Furthermore to provide a jack which-embodies therein a hydraulic: cylinder from which a-lifting-piston-rcdiextends and wherein the cylindere'has a-base .for its support that is fixed :theretoadjacent that-v end from which the rod-extends as differentiated from the usualhydraulic or screw-jack design having-afiared base: atthe end of thejackbody or-cylinder opposite a that fromwhichthepiston rod or screw extends.

It is also anobject of this invention to provide a hydraulic jackv comprising "a jack cylinder wand a piston rodextended from: one end thereof -;a nd

a 1 supporting 'base for the -cylinder-"fixedabout the .upper end of-the cylinderand which base is hollowand serves also as the reservoir for the;

hydraulic medium and as :a support or=mounting for a; handoperated pump :mechanism whereby theshydraulic; pressure medium i may be forced into the cylinder for the extendingwof-the jack.

It-is alsoanobject of-this-inventicn to provide a hydraulic jackthat :is: especially adapted forheavy; commercial liftin operations,- that is easy tozmount, convenient-tense; compact: in design;

powerful in. its lifting function, that can be quickly retracted and which provides both for precision lifting or lowering.

Still another'objectl'of the invention is to pro-- viden jack'oflthe kind above-stated that may be: used in- Vertical or 'horizontal position, and" for various power applying operations;

Other objects of the invention reside in the dev tails-of construction'andcombination of its parts and the mode of use-of.th'e=j ack-as:willhereinafter be fully. described.

In accomplishing-- the above mentioned and other-objectsrof the invention-,- I: have'providedthe improved details of construction; the preferred; forms; of which are;-il lustrated inthe; ac.- mpanyinsldrawinss; vli reinn Fig: 1' isx'a; view showing-partiallyin elevation and: partially in; longitudinal section, aqjackw mechanism embodied by;the-presentinvention. 1

- Fig; 2 isasectiona-l detail of analternative'form oiipower pumpirmecha-nism:adapted for use withj crsa t;tnepre en zkin -i,

Eig ,3 is a:top; OI' PIaII' ViQW of the iack asrsupp rted-bycribbinsziorusa Fig.4 is;-a horizontal cross section taken-0111111 in Fig l as being closed at its lower end by'a plugs; ll thatqis threaded and welded inthe end of the;- cylinder body; Reciprocally ccntainedinthe cylinder and extending from its upper endis a-piston;

rod l2 having a suitable headupacl ing or gasket;;

asat H3, at its lower end. The packing-washer ishere-shown as beingheldoinrplace by anover z lying washer M and a nut l5,a that are applied-to; astud 15 that extends from the lower end -o f-th rod and through the packing, and washer as seen in Fig. 1

At itsupper end, the piston rod- I Zpasses;v

through a packedglanddt-that is threaded into th upperend of thecylinder. It isshown also infF ig. 1 that thererissligh-t clearancebetween therod and cylinder wall ;for escape of hydraulic;

mediumthat may be forced past the-par-zlging I 3;

as presently explained.

Secured solidly to the upper end portion of the I cylinder and extending in a p1ane=perpendicular-- tothe cylinder axis is thesupporting base,=or-,-

mounting member, for the jack: This base is-de-V signated in its entiret .by reference characterzfl and it is fabricated of sheet metal plates or might be castsofrmetal. In planasnoted in Fig. 3; this a base is substantially square and the 'jackcylinder; passes centrally therethrough and is fixed solidly thereto: As-shown best in Fig. 1, pthejackv- Cy11i1-,1-. derhasa circumferentialshoulder Zl about its upper end againstwhich the base engages, and-1 the lower wall otthis base: is welded, as at-n to the jack cylinder.-

It is shown in Fig. 1 that the base 213 ishollow thereby forminga reservoir 23 fora supply of hydraulic pressuremedium as indicatedat 25.

' Thisbasegisvhere shown as being in theshape.

of a truncatedpyramid, with a flat bottom sur face.- that extends substantially to all sides .of, the cylinder, thusprovidingthat the jack maybe substantially; mounted on cribbing blocks asr shown lnFig. 5.; giving adequate support-forthe jack and reducing to considerable extent the distance betweenthe-planeof support anciuztl ae;

po'iht of contact with the load to he lifted, thereby\insu-ring; aminimum tendency of-.the -j ack to -tip1sideways; und 1 heavy lifting pressure.-

have here hown. jac p ston; as bein ot ippedat itssuppe nds th i ocke 25 was taining a ball bearing 21 against which a socketed bearing plate 28 engages, and which plate would engage the object to be lifted.

To eifect the extending of the piston rod for lifting a load, I have provided the jack with a hydraulic pump mechanism as shown best in Fig. 1, this comprising a block or housing 3% that is fixed to the under side of the base member at one side of the cylinder,-as best shown in Fig. 1. Formed in this block and extending upwardly therefrom and through the top wall of the base, is a pump cylinder 3| in which a pump.

piston rod 32 is reciprocally mounted.

Also formed in the block, and opening at its upper end into the supply chambers 23 for the hydraulic pressure medium, is a channel 33 which at its lower end leadsinto a valve" chamber 34 which, in turn, opens into the lower end of the pump cylinder 31!. Contained in the chamber 36 is a backcheck valve 35 that opens to admit liquid from the supply chamber to the lower end of the pump cylinder, but which closes automatically to'prevent any return flow. Also, communicating directly with the lower end of the pump cylinder 3| is a channel 36 that leads from the block into a channel 3'! that leads along the outside of the cylinder wall and at its lower end opens into the lower end of the jack cylinder throughthe plug H. The channel 36 contains a spring pressed back check valve 38 therein that prevents any return flow of hydraulic medium through the channel.

It is also shown in Fig. 1 that a by-pass channel 40 leads from the chamber 23 to the channel 36 to provide for a quick return of the hydraulic medium from the lower end of the jack cylinder to the supply chamber when quick lowering of the jack pistons is desired, but which by-pass channel is normally closed by a hand operated valve mechanism indicated at in Fig. 1.

This valve mechanism comprises a threaded valve stem 45a adapted to be turned by hand wheel 45!; from and against a valve seat 47 at the juncture of the by-pass channel with the channel 36.

At its upper end, the pump piston rod 32 is pivotally connected, as at 48, with a hand lever 49, which lever, in turn, has a bifurcated inner end portion pivotally connected, through linkage 50, with lugs 5| that are fixed 0n the top wall of the base member. Up and down action of the hand lever 49 will effect a reciprocal action of the pump piston whereby liquid upon upward travel of the rod, will be drawn from the supply chamber through channel 33, past valve 35, into the lower end of the cylinder 3l;' then when rod 32 is forced downwardly this liquid will be forced through channels 36 and 31 into the lower end of the jack cylinder ID to eiTect the lifting of the jack piston rod.

It will be understood that the hand lever may be extended to any practical length in order to obtain a desired leverage. After a load has been lifted by upwardly extending the jack piston, and should it be desired to lower the jack, the valve 35 is opened and the hydraulic medium will be 6! that is threaded into a side wall of the plug. In the latter plug, a seat is formed for the back check valve.

It is noted also in Fig. 1 that there is a bleeder port 66 opening through the jack cylinder wall near its upper end into a channel 61 that leads into the supply chamber, permitting any hydraulic medium that may leak past the piston packing I3 to be returned to the supply chamber.

In Fig. 2, I have illustrated an alternative pumping mechanism in which high pressure and low pressure pumps have been incorporated in a block 30c which would correspond to block 30 of the jack of Fig. 1. This block is formed with a pump cylinder '70 of small diameter, and a pump cylinder ll of larger diameter; the cylinders con "tain pump pistons '12 and 13, respectively, de-

. bottom wall of the chamber.

signed to be operated individually by hand lever mechanism as previously described. The pump of larger diameter would be used when the load to be lifted is rather light, and the pump of smaller diameter would be used when the load is extremely heavy. As shown in Fig. 2, both pump cylinders open at their lower ends to a common passage 15 which connects with the lower end of the jack cylinder, in the same manner as channel 36 is connected in Fig. 1, and this connection embodies a back check valve 18 therein corresponding to back check valve 38.

It is shown also in Fig. 2, that the two pump cylinders are supplied both with liquid from chamber 23 through a channel containing a back check valve 8i corresponding to the channel 33 and check valve 35 of Fig. 1. I also pro-' vide a hand set valve 30 which may be adjusted to a position to close ofi the pressure from the high pressure pump to the low pressure pump as a precautionary measure, if such is desired.

As a detail of construction, it is shown in Figs. 1 and 2, that the upper end of channel 33 opens into the chamber within a semi-circular channeled ring extended about the cylinder as in Fig. 2, and which channel is open to the under side of the ring and to a sump 96 in the stances, if the object was close to the ground.

it might be necessary first to dig a hole to contain the lower end of the jack therein.

It is to be explained further that lacks of this kind can be used in various ways other that illus-- trated in Fig. 5. Where conditions are satisfactory and the load light the lower end of the jack cylinder might be set directly upon a support.

If it should be found desirable, the jack could be used in a horizontal position, for pushing 01' even in an inverted position for lifting.

Jacks of this character may be made in various sizes and equipped with the single or dual pump mechanism.

One of the principal'advantages of the present construction and arrangement is thought to' re-' side in the relationship of the supporting base structure to the jack cylinder and in the utilization of this hollow base as a reservoir or chamber for the hydraulic pressure medium. The placing of the base close to the upper end of the jack gives stability to the jack in use, and fur-- thermore permits the'lower end portion. of the jack to be placed in a hole if such should be re- A removable plug quired in order to lower the jack sufliciently to get under the object being lifted.

Insofar as the advantages of placing the base near the upper end of the jack cylinder are concerned, this same construction is applicable to jacks of other types; for example, the well-known type of screw jack, and it is not desired that insofar as claims to this part are concerned, that they be restricted to hydraulic jacks but that they shall be applicable to any jack Where the lifting shaft or piston is extendable from a mounting house.

Having thus described my invention, what I claim as new therein and desire to secure by Letters Patent is:

l. A jack of the character described comprising a hydraulic jack cylinder of substantial length, a piston operatively fitted in the cylinder and extended from th upper end thereof to engage the object to be lifted and terminating substantially flush therewith when fully lowered, a supporting base for the jack in the form of a hollow flange and affixed rigidly to the cylinder about that end portion from which the piston extends and having a chamber of substantial volume therein for a supply of hydraulic pressure medium, and a pump mechanism mounted on the jack and operable to deliver hydraulic pressure medium from the said chamber into th cylinder to extend the piston in a lifting operation.

2. A jack of the character described comprising a hydraulic jack cylinder of substantial length, a piston operatively fitted in the cylinder and extended from an end thereof to engage the object to be lifted, a supporting base for the 35 Number jack in the form of a hollow flange afflxed to the cylinder about that end portion from which the piston extends and extending to all sides thereof and having a chamber therein for a supply of hydraulic pressure medium, and a pump mechanism mounted on the jack base and operable to deliver hydraulic pressure medium from the said chamber into the cylinder to extend the piston in a lifting operation, and there being a channel in said pump mechanism for return flow of the hydraulic medium from the jack cylinder to the chamber, and an adjustable valve for controlling the rate of return flow of liquid therethrough.

3. A jack of the character described comprising a hydraulic jack cylinder, a piston operatively fitted in the cylinder and extended from an end thereof to engage the object to be lifted, a supporting base for the jack surrounding the cylinder about that end portion from which the piston extends and having a support engaging surface that is perpendicular to the axis of the cylinder and a chamber therein for a supply of hydraulic pressure medium, and a pump mechanism mounted on the jack and operable to deliver hydraulic pressure medium from the said chamber into the cylinder to extend the piston in a lifting operation, and means on the said base for the manual actuation and control of the lifting element.

FRANK CURTIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date 1,474,834 Heil Nov. 20, 1923 2,261,438 Harwood Nov. 4, 1941 

